Hopper car



April 10, 1928.

v. WILLOUGHBY HOPPER CAR Filed July 20. 1923 5 Sheets-Sheet 1 April l10, 1928.

V. WI LLOUG HBY HOPPER CAR April 1o, 192s. 1,665,388

V. WILLOUGHBY HOPPER CAR Filed July 20: 1923 5 Sheets-Sheet 3 /NVENTUR April 1o, 192s.

V. WILLOUGHBY HOPPER CAR Filed July 20, 1923 5 Sheets-Sheet 4 -April 1o, 192s. 1,665,388

V. WILLOUGHBY HOPPER CAR Filed July 20, 1923 5 Sheets-Sheet 5 /NVE/VTR Patented Apr. 10, 1928.

l,6ti5,388 :Paire-r oer-ies.

vrcrronwrmoeirsr, "or "aI nGn-i voo/D,ffi\inw zr-nnsar, essienon "ro AMERICAN cnn AND FOUNDRYCOMPANY, or NEW YORK, n. Y., n conroaarrou or NEWJERSEY.

` 'Hoeren 'cna'.

preferred 'form' of the `inifention,"though it is to =be understood that lthe invention isnot limitedto the :exact details of construction shown and described, 'as it 1is obvious that various 'modifications thereof Within the scope 'of the iclaims will Voccur-Sto persons skilled in the art.

lns'alid drawings:

Fig. 1 is-asideelevation-of 'a hoppercar constructed y'in accordance With my invention, certain portions being broken `away to. showthedoor operating mechanism parts in assembled relation and mounted 1in service 'position 5 Fig. Q is a plan view of'a. Iportion of vthe car with certain :parts lbroken avvayto more clearly show the application of 'the door operating mechanism Fig. 3 isa verticalsectional View taken on line 3-3 of'fFig. 1,lookin'g inthe direction indicated -by the 'arrows and showing the paivl, door operating, and crankshaft elements of 'the door fmechanism, and portions 'of the endfloor and side Wallsbroken away to show the side Wall assembly;

on line 4h4- of Fig. 3, looking in the direction indicated by the arrowandshoivingthe crank shaft and door 'link connections;

Fig. 4 is a'sectional view taken on line in- 4u of Fig. 4L, looking in thefdirection indica-ted by the arrotv and showing the crank frame vand door link connection mounted upon the 4bearing bracket;

Fig. 5xis a vertical-sectional View taken on line 5-5 of Fig. 2, looking in the direc-v tion 'indicated by the arrow and'shovving the stop `lug of `the crankshaft Within EJthe sprocket Wheel and Figs. 6 to 1l inclusive represent the Vposi-v tions of the crank shafts at opposite ends of the doors, the sectional Vviews corresponding to one on 4Vline 7 7 of Fig. 5, and show, in Figs. Gand 7 the relative positions of shaft lug and sprocket Wheel just prior vto the door unlocking movement, Vand in Figs. 8 and 9 the position 4of shaft tafter dropping of the doors, and Figs. I1() and 11 show the relative positions "of shaft iand 'sprocket Wheel when doors have been raised and shafts locked.

My invention relates to lthat class of hop# per bottom 'cars used primarily in the ore carrying 'service and hasfor fone of lts ob- The accompanying drawings illustrate `the 1923. `serial ino. 52,733.

the-hopper type having a sing-le I:discharge i opening 11 in its bottom, ythebottom vbeing-l closed by a Lpai'r of'doors 12 hinged/at the car 'sides and meeting -With 'their free edges at "the `'longitudinal center of theA car.

The discharge openingTl is deiinedbyfthle hopper side sheets 18 and the sloping end sheets 14. The doors 'extend the ventire length ofthe door opening-and. are fofsiiiiicient strengthto carry the load` upon them, being iprovidedv with door` stiifeners 15 along theirfrec edges andbraced-by hinge mem-A bers 16 secured to the doors transversely thereof. The hingemembers '16 are-pivoted at 17 to hinge brackets F18 secured to the inner longitudinal side sill members 19 of the car'underfraine 9. The ldoors -are hung adjacent the hopper side sheets 'lvvhich ter- Fig. 4. is a vertical sectional vieri7 takenminate in a plane above the 'edges of the sloping end sheets "14, permitting vthe doors to assume a contour substantially angular'in cross'section morder lthat thespace between.

. ings as forming extensions `of the door stift eners 15, designed tov afford 4attachment-'for the door links 21. Thedoor links comprise the jaws 22 pivotally connected tothe door projections v20 yby pins 28, the `yoke piece 24 mounted on pin AQfhaving 'la bearing -in the..

crank frame 26, and link rods 27 pivotally secured to lthe Ayoke rpiece 24 and `pivotalfly and adjustably secured at'thei'r lovver ends to the jaws 22. This arrangement permits-free play of vthe door links throughout the Afull range'of door travel and-crank vframe move.

ment.

The crank frame 26 comprises the arms 2S connected by a web :Q9 'extending along one edge of said'arms. The arms `are `pro:- vided ivith integral vtrunnion portions 30 journaled in Ia bearing bracket BA1 :designed toconnect-theslopingiend -floors flfifand draft members 32of the underframe 9. The bear'- ing bracket transmits lthe load-on the crank l oo ` rivets 33 and 34 respectively, connectingthe disengaged from their bearings 35.

end floor and draft members to the bracket.

The bearing bracket 31 is provided-with a pair of inwardly extending trunnion bear ings 35 open preferably at the upper sides 36 of such inwardly extending portions to allow the passage downwardly of the trunnions 30 during the process of assembling said parts. The trunnion bearings are fitted with removable bushings 37 adapted to receive the trunnions 30 over their peripheries to provide positive means for holding the crank arm trunnions 30to their bearings 35. Any tendency on the part of the trunnions to leave their bearings would be resisted by the inwardly projecting bushings 37 whose upper vsides 38 extend above the trunnions. held down bythe engagement of thetrunnion bearings 35 withthe inner ends of the upper side portions 38 of the bushings. The bushings 37 are prevented from moving inwardly by the crank arms 28 with which the bushings will contact before they become The bushings are held from outward movement at one side of the crank frame by means of stop `plates 39 secured to the bracket 31 by bolts 40, `or the like, and on the opposite side by a washer 41 secured by a cotter 42 to a crank shaft 43 of the crank frame 'open ating mechanism hereinafter to be described.

lVhen mounted with their trunnions journaled in brackets 31 underlying the sloping end floors 14 of the hopper, the crank frames 26 are in condition to be actuated by the operating mechanism to rotate about their bearings from their lockeddoor supporting ,po-V

sition shown in full lines `in Fig. 4 to-their released load discharging position shown in broken lines of that figure. In their door supporting position the crank frames lie with their connecting web portions 29 against the uppermarginal edge 44 of bracket 31. In this position the door links 21 lie in a plane passlng through crank pin 25 and jaw pins 23 and inside of a plane through the axial center of the trunnions `30, tending thereby to induce rotation ofthe crank frames toward the hopper end floors 14 and `lockingthem against reverse movement until forced outwardly beyond the dead center of the parts whereupon such parts will move under the weight of the load to release the doors to discharge the lading. Y y v The operating mechanism comprises a pair of crank shafts 43 arranged transversely of the car and mounted adjacent the underside of the sloping end floors 14 and journaled at their outer Vends in bearings 44EL secured Vto the outer longitudinal side sill members 45 and engaging at their inner ends with re- The bushings themselves are 51 `and 52 providing a loose connection between the crank shafts 43 and an operating shaft 53`to permit the dropping of the doors and rotation of the crank shafts 43 without communicating such movement to the operating shaft 53. l

The driven sprockets are loosely fitted to the crank sheets 43 as shown "in Fig. 5 and areformed tointerlock with the shaft lugs i 49 for limited rotation on the shaft and to prevent vshifting thereof longitudinally of the shaft. The saidV sprockets are mounted in a. plane adjacent the car side and are connected together' by a link belt v mechanism 54 for the simultaneous operation of the crank frames 26 at opposite ends of the hopper, the link belt connection being so designed as to effect the relatively opposite rotation of the crank shaft sprockets,` crank shafts, and crank frames' 26, re-` spectively. i

The link belt 54 is continuousand extends from the upper side of the driving sprocket 55 on theoperating shaft 53 directly to the upper side of the crank shaft sprocket 52 at the opposite end of the hopper, thence about the peripheryof said sprocket 52 to the underside thereoffrom" which point the belt returns in the direction of sprocket 51 to engage the upper side of saidl wheel thence to the underside of the driving sprocket 55 onthe operating shaft 53. To insure positive engagement of belt and upper peripheral `portion of sprocket 51 an idler 56 is .employed to` hold the belt to the sprocket.

The idler 56 is secured to the underframe` 9 by bracket 57 and lies above the lower strandrof the continuous belt 54 as shown in Fig. 1 and effectuallyv guides the `belt to the sprocket 5l* At points intermediate the guiding idler` 56 and the lower peripheral side of sprocket 52, thelower strand of the link `belt is supported upon rollers 58 journaled in brack` ets 59 secured `to the car underframe 9, while the upper strand of the link beltis support- 1 ed intermediate the sprockets-52 and 51 upon rollers 60 journaled -inbracketsw 61 secured to the framing gusset braces'62 having open-` ings 63 through which the belt passes.` AThe link belt 54 is partially made up of connecting rods 64 in those portions thereof which play between the sprockets and is `adjustably lll) mounted by means of the turnbuckles 65 con# necting adjacent ends ofrods y64 in both upperand lower .portionsfof the belt.`

The operating shaftv53 extends from side to side of the: carand has fixed thereon the driving sprocket 55 adjacentto the crank shaft sprocket 51 and in 'position to engage the belt 54. lAdiacent 'the driving sprocket 55 `is fixed a ratchetwheel 66 designed to engage a locking pawl'67 fixed tothe adjacent end of a pawl shaft 68e paralleling rvthe operating Vshaft 53l and also `'extending from side to side of the can and operable from either sfide. VThe pawl 67 is actuated by a handlef69, preferably integral lwith the pawl and serving as a counterbalance .to either hold said .pawl `in engagement Awith the ratchet wheel66 or out of contact therewith. The pawl handle 69 is `provided with a tooth portion 70 adapted to engage the teeth -of the ratchet wheel before the dead-center position of the crank-frames vand door links is reached to check the backlash ofthe ratchet wheel 6'6 during the Yinitial door opening movement of the operating shaft.

The operating `shaft is 4provided with square ,ends to facilitate operation from either side of the car by means of a removable lever (not shown). j The pawl shaft 68 is `equipped with an additional counterbalance and operating handle 7l fixed lto the shaft whereby the ratchet pawl 67 and pawl handle 69 may yalso be actuated from the side opposite to the transmission side of the car. mounted for rotation in bearing brackets 72 and 73 secured to the side sills and at their intermediate Aportions in a bracket 74 ksccured. to oneeofrthe draft members 32 ofthe unnderframe 9. p

Assuming the doors to `be in 'the locked raised .position shown in Figs. l to 4 inclusive, the doorsare released tol drop the lading by firstr rotating the Tpawl shaft 68 by means of eitl1er counterbalance handles 69 or l to disengage pawl 6-7 from Athe `ratchet wheel 66 and cause the tooth portion 70 of the handle 69 to engage the ratchet as-indicated at ythe right ,hand side of Fig. l. The operating shaft y53 being thus lreleased for rotation the shaft is rotated by means of `a lever fitted over a square 'end thereof. rlhc rotation ofthe shaft is `in the direction of the center of the car causing the lower porf tion of the link Vbelt l54 to rotate the sprockets 52 and 5l in relatively opposite direc` tions ,and away from the hopper end kioors as indicated by the arrows in Figs. 6 and 7, respectively. j

Prior to .the beginning of sprocket `move ment the crank shafts 43 -are locked 'against rotation 'by means of the -lugs 50 of the,

sprockets bearing against the lugs 49 of the shafts as shown in Figs. 10 and 11. Upon rotation of the sprockets in vopposite direc- Both operating and pawl shafts arel tions, as above described, the lugs 50 on 'the sprockets first move -away from one side of the temporarily stationary `crank shaft lugs 49 to the opposite side of said lugs as Vshown in Figs. 6 and 7 During this movement the sprockets will jhave rotated idly upon 4the temporarily stationary crank :shafts under the influence ofthe link 'belt movement and the crank shafts released ito permit rotation thereof.

Continued rotation of the sprockets in the direction indicated by the arrows in Figa. 6 and 7 will cause their respective 'crank shafts to rotate in the direction indicated by the Varrows in Figs. 8 and 9. During this movement the driving Aforce of the sprocket lugs dagainst the lugs 49 on the crank shaft will have vcarried the crank frames 26 .past their dead-center 'posi-tions onthe shafts after which gravity will operate to cause said crank frames to yield to the weight of t-he supportedloadand Vmove to the released position indicated Ain broken lines in Fig. 4 whereupon the ldoors w'gill drop to the broken line posi-tion Iindicated `in Figs. l and 3.

Immediately upon movement -of the Vcrank shaft under the inliuence-of the downwardly moving doors, no vfurther 'manipulation of the operating mechanism will benecessary, the sprockets remaining stationary from the inception of such movement to its consummation. During this period of'rotation "of the crank shafts in the direction Aindicated by the arrows in Figs. 8 Aand 9 the llugs 49 thereon will race away from the lugs 5() on the relatively stationaryV sprockets until they assume the position shown in said figures, the doors drop to discharge the lea-ding.

To raise the doors, the counterebalance handles 69 and 7l Aarethrown from their unlocking position shown in dotted li-nes in Fig. l to their initial r`ratchet locking position shown in full lines in Athat ligure. This movement rotates the pawl shaft 68 and -car ries the ratchet pawl into engagement with the Vratchet wheel 66 `to tlock the operating shaft against rotation inthe opposite Akdireci n d o ytion durino' the door raisinc` operation. The

operating shaft 53 is then rotated ina -dsi'rection away fromthc hopper to-eflecta reverse vmovement of the link belt '54 causing rotationfof the sprockets in Ythe direction yindicated by the arrows lin Figs. 10a-nd 1l. 'Con-- tinuing thus to rotate the 'operating shaft 53 will cause the sprocket lugs 50 to lexert a driving force against lugs 49 on the `crank shaft causing the -cra'nkshafts to rotate to return the crank frames 9.6 and the'doors to their raised and locked p'ositio'n as shown in -F-igs. l. 3 and4.

It will be Tnoted lthat `to effect the Arelatively opposite movement of the 'crank shafts 43, one of said shafts, preferably `the one adjacent the operating shaft 153, vis arranged f outsideV of the link belt area. Instead of embracing the ISprocket 51 and respective shaft 43 as in the `case of sprocket 52 with respective shaft 43 at the opposite end of the transmission, the belt 54 is deflected from its course adjacent the sprocket 51 and directed to the upper peripheral side `of said sprocket 51 and held and guided thereon by means of the idler 56 before mentioned.

The inner pair-s of wheels 8 of the supporting trucks are shielded from the discharging lading by a pair of baffle plates 7 secured adjacent the discharge opening 11 to the sloping end Hoor sheets 14 and to the inner longitudinal side sill members 19.

The side Walls of the car body are braced against bulging by a. structure including the inside stiffeners 2" supplementing the framing gusset braces 62 and the top chords sui-mounting the side wall plates 5. The top chords are of a general triangular' con figuration with a vertical side portion 4 secured to the outer face of the side wall plates and an inclined portion 3 extending downwardly and inwardly7 from d vertical portion, the vertical and inclined portions being connected together and to the adjacent side wall plate'5 by a horizontal base plate portion 2 provided with a marginal flange 1 lying against the inner face of the side Wall and there secured by rivets SO to the adjacent wall plate and vertical side' 4 of said chord and to the inside stiffeners 7 shown in Fig. 3. Thus arranged, the gusset braces 62, inside vertical stiffeners 7, and top chords 6, with the hopper side sheets 13 and side wall plates 5 connecting them, provide a rigid structure within the lines of maximum width of the car to prevent distortion of the car body under impact of `the lading dropped from the loading buckets or from contact with the buckets themselves during the loading operation, and against the racking stresses of draft and buifing service. j

Vhat I claim is:

1. A hoppercar having a single discharge opening, a pair of drop doors closing said opening and hinged longitudinally of the car, crank shafts mounted at oppositeends of the discharge opening and connected to the doors, an operating shaft, sprockets on said crank and operating shafts, a continuous chain power transmission connecting all of said sprockets and loose connections between said crank shafts and their respective sprockets.

2. A hopper car having a single discharge opening and a pair of longitudinally arranged drop doors hingedat the car side and closing said opening, crank shafts arranged .transversely of t-he car adjacent the opposite ends of said opening and connected to the doors, an operating shaft adjacent one of said crank shafts, and transmision vmechaincassa nism connecting said operating shaft and one of said crank shafts and means adja` cent the other of said crank shafts to hold said transmission mechanism in operative relation thereto whereby relatively opposite rotation of said Y crank shafts isv effected.

3. A door operating mechanismv for hopper car doors arranged longitudinally `of the car and including a. pair of transversely extending crank shafts adjacent the opposite ends of said doors, an operating shaft, loose connection devices on said crank shafts, transmission mechanism connecting said crank and operating shafts through the inedium of said loose connection devices, and means adjacent one of said crank shafts to hold said transmission mechanism in operar` tive relation thereto whereby relatively oppositevr rotation of said crank shafts is effected. j j' 4. In a door operating mechanism for drop doors, crank shafts connected to the free edges of said doors, an operating shaft, transmission mechanism connecting said crank and operating shafts, loose connecting devices between said transmission mechanism and said crank shafts, and means intermediate said crank shafts to hold said transmission mechanism in operative relation to one of said crank shafts wherebyv relatively opposite rotation of said crank shafts is effected. j j

5. In a dooroperating mechanism for cars having a pair of longitudinally arranged drop doors adapted to drop away from each '10U other, crank shafts adjacent the ends of the doors and extending transversely of the-car, an operating shaft, link belt mechanism con-y necting all of said shafts and loose connection devices between said link belt mechanism and said crank shafts. Y.

6. ln a door operating mechanism for drop doors, crank shafts connectedrto the free edges of said doors, an operating shaft, link belt mechanism connecting said crank and operating shafts, loose connection devices between said link belt mechanism and i.

transversely extending crank shaftsA adja-v cent the opposite ends of said doors, an operating shaft, loose connection devices on said crank shafts to permit limited rotation of said crank shafts 'independently' of the operating shaft, transmission mechanism `connecting said operating shaft and one of said crank shafts, and means adjacent the other of said crank shaft to hold said trans- `mission mechanism in opera ive relation thereto for effecting relatively opposite rota` vtion of said crank shafts.

8. `A hopper car having a single discharge opening and a pair oflongitudinally arranged Vdrop doors hinged at the car side, transversely extending crank shafts adjacent the opposite ends of said doors, an4 operating shaft, transmission, mechanism connecting .said operating and crank shafts, loose connection devices between saidV transmission mechanism and said' crank shafts adapted tov effect simultaneous rotation of said; crank and operating shafts, and means adjacent one ofv said crank shafts engaging said transmission mechanism-with saidy crank shaft whereby relatively opposite rotation of saidv crank shaftsis effectedl 9i In a2 hoppercar having hopper side and sloping end floor sheets defining a singleldischarge opening and a supporting underframe, aI pair oflongitudinally'arranged doors closng said'opening, brackets connecting the sloping end floor sheets and underframe yand provided with inwardly extemlingvv trunnion bearings open their tops, crank arms having integral'trunnionsmounted for rotation in said bearings, and bushings securing said crank arms in said bearings, said crank arms having supporting connection with said doors.

10. The combination with the drop .doors ofy a Ahopper car having a single discharge opening and a supportingunderframe, of brackets supportedon the under-frame adjacent the endsof' said opening and' provided with inwardly extendingv trunnion bearings open at their tops and fitted with removable bushings, crank arms having integral trunnions mounted for rotation in saidbearings, said bushings being adapted to receive said trunnions over their peripheries. j

1l. In a door operating mechanism for cars having a pair of longitudinally ar# ranged drop doors, crank arms connected to oppositeends of said doors andl mounted for rotation to raise and lower the doors, crank shafts extending transversely ofthe car and having operative engagement with the respective crank arms, loose connection devices on said crank shafts permitting limited in; dependent rotation of said shafts, an operating shaft, flexible transmission mechanism connecting said loose connection devices and through them the crank shafts and means holding said transmission mechanism in operative relation with one of said loose corr nection devices whereby relatively opposite rotation of the crank shafts is effected.

12. In a dumping car having a single discharge opening and a pair of longitudinally arranged doors closing said opening, a pair of oppositely rotatable crank shafts con nected' to said doors adjacent the opposite ends of said opening, a. continuous operating means connecting said shafts having upper and lower strands and means engaging one of said strands of said operating:

doors, shaft rotatingV sprockets loosely` mounted) thereon, a continuous connection for said sprockets having upper and lower strand portions, and,V meansy engaging, the lower strand'` ofsaid connection adjacentjone of said' sprockets permitting deflectipu of said lower strand to engage the upper peripheral side of'said. sprocket for effecting relatively opposite rotation of said crank shafts.

ljt'. Ina dumping car' having a pair of longitudinally arranged dropv doors and mechanism for operating saiddoors including a pair ofv transverselyv arranged crank shafts adjacent the opposite4 ends of said dOO-IS, Shaft rotating Sprockets loesely mounted thereon, va continuous connection for said sprockets havingupper and lower strand port-ions, an idle roller'above the lower strand of said connectiony adjacent one of said sprockets for deflecting said lower strand to the upper peripheralside of said sprocket for .effecting relatively opposite rotation of said' crankshaftsl and an operating shaft having a sprocket engaging said continuous connection.' 'Y

15, In a dumping car having a pair` of longitudinally arranged drop doors and mechanism. for operating said' ,doors` in,- cluding a pair of transversely extendinof crank shafts adjacent the opposite'ends oit said doors, an operating shaft adjacentto oneof said crank shafts and fitted with, a driving sprocket fixed to one end thereof, shaft rotating sprockets loosely mounted?r on said crank shafts, a continuous connection for said' sprockets andY operating shafthaving upperl and' lower strand portionsa nd an idler above the lower strand of said connection .adjacent oneY of' said@ sprockets for deectessed 10W/Q1? Strand t0 the. upper peripheral side of'said sprocket for elfect ing relatively opposite rotation of said crank shafts, the upper strand of said connection having direct uninterrupted engagement with the driving sprocket on said operating shaft.

16. In a dumping car having a pair of longitudinally arranged drop doors and mechanism for operating said doors including a pair of transversely extending crank shafts adjacent the opposite ends of said doors, shaft rotating sprockets loosely mounted on said crank shafts, a continuous connection for said sprockets having upper and lower strand portions, an idler above the lower strand. of ctiiiietion adja cent one ofsaid sprockets for defiecting said lower strand tothe upper peripheral side of said sprocket for effecting relatively opposite rotation of said crank shafts andan operating shaft having a driving sprocket xed to one end thereof, the upper strand ,portion of said connection providingdirect and uninterrupted engagement between the driving sprocket on the operating shaft and the sprocket on the other of the crank shafts, said crank shafts being adapted torotate independently ofsaid operating` shaft.`

`1'?. In a door operating mechanism `for cars, a pair of crankshafts extending transversely of the car and connected` for simultaneous operation, an operating'shaft having a ratchet wheel fixed thereon operatively connected to said crank shafts, and a locking shaft having ratchet pawl mechanism arranged to engage said ratchet wheel to lock said operating shaft against reverse rotation during the door raising operation, saidlocking pawl having a handle portion provided with a ratchet engaging tooth for checking` the reverse rotation of the operating shaft during the initial door `releasing movement `of the. operating shaft.

18. A car having a discharge opening,

doors for said opening, crank shafts operatively connected to said doors, an operating shaft, sprockets on each of said shafts and `underframe and having trunnion bearings open at their tops, crank arms for` operating said doors having trunnions rotatably mountedin said bearings and `bushings between said trunnions andbearings retaining Asai-d trunnions in position.

21. car having a discharge opening, doors for `said opening, crank shafts for o erating said doors, an operating sha t,

sprockets on said shafts andv a continuous powertransmitting means connecting all of said sprockets and y. operating saidV crank shafts in opposite directions.

22.`A car having as discharge opening,

doors for said opening, crank shaftsfor o 7 erating said Idoors, an `operating sha t, sprockets on said shafts and power.` transmitting means connecting said sprockets,

said crank shafts and sprockets having a loose connection permitting movement of saidcrank shafts independently'of said operating shaft.

23. In a car, door operating crank shafts, an operating shaft operatively connected to said crank shafts and having a ratchet wheel fixed thereon, a locking pawl for said ratchet wheel to prevent rotation of said operating shaft in one .directionand an operating handle for said pawl, said handle being operable to engage said ratchet wheel to `prevent rotation .of `said operating shaft in the opposite direction.

24. A hopper car having a `discharge opening, drop doors closing said? opening, crank shafts connected to saiddoors, an operating shaft, a sprocketron each of said shafts, a chain power transmission engaging all of said sprockets anda loose connection between each crank shaft" and its sprocket.

25. In a door `operating mechanism for drop doors, ,crank shafts connected to the free edges ofsaid doors, an operating shaft, sprockets on said .crank and operating shafts, loose connection devices'between said. crank shafts `and-their sprockets, a power transmission` mechanism engaging all of said sprockets and means intermediate said cra-nk shafts to hold said transmission mechanism in operative relationrto one of said sprockets, whereby relatively opposite rotation of said crank shafts is effected.

In witness whereof I have hereunto set my hand.

VICTOR WILLOUGI-IBY. 

